There are applications, such as certain electric switches, for example, requiring activation of a rotor that performs a turning movement inside a fixed stator for connecting and disconnecting internal contacts. The generation of the actuating or operating movement is particularly problematic in special applications, for example when helicoidal movement of the rotor is to be obtained, because in that case it is necessary to have mechanical devices generating said helicoidal movement by means of transforming rotational movement, conventionally provided by an external switch actuation mechanism.
A simple way to achieve said helicoidal movement from a turning movement would be to provide a screw and a thread, such that when rotating the screw inside the thread, forward movement along the axial axis is added to the rotation, achieving the desired helicoidal movement. Nevertheless, this solution has a series of problems and limitations. First of all, said solution is only valid for systems requiring a reduced forward movement along the axial axis.
However, for applications requiring considerable longitudinal travel associated with a small angular turn, as in the case of a rotary electric switch, the thread pitch necessary for achieving said transformation exceeds the limitations of existing machinery for machining screws, i.e., the machinery existing today is unable to obtain large thread pitches. For example, by using a lathe to obtain said threading, an extremely rapid rate of forward movement of the cutting tool with respect to the turning of the part to be threaded would be necessary for the part acting as a nut which has an inner machining, and machinery that is capable of performing said task is currently unknown.
In the second place, the longitudinal forward movement direction is determined by the turning direction of the screw. In other words, in the event of continuous rotational movement in a single direction, the screw will move forward or backward until reaching maximum travel. Once said maximum travel has been reached, it is necessary to change the direction of the rotational movement of the screw to generate helicoidal movement in the reverse direction. However, there are applications in which rotational movement in a constant direction has to be transformed into helicoidal movement incorporating a back and forth or reversible movement. In other words, once the maximum travel has been reached, the helicoidal movement continues without stopping but it changes to an opposite longitudinal direction without modifying the turning direction for that purpose.
Therefore, there is still a need in the state of the art for an actuating device that is able to transform rotational movement into helicoidal movement and back and forth movement, furthermore being able to obtain considerable longitudinal travel with reduced rotation.